magistrsko delo
Svit Menart (Avtor), Klemen Pirnat (Mentor), Iztok Turel (Član komisije za zagovor), Janez Cerkovnik (Član komisije za zagovor), Jernej Iskra (Komentor)

Povzetek

Trenutno uporabljani akumulatorji v električnih avtomobilih vsebujejo anorganske katodne materiale na osnovi kovin prehoda. Kot alternativo anorganskim katodnim materialom se v zadnjih letih izpostavlja organske katodne materiale, katerih prednost predstavljajo nižja cena, višja teoretična kapaciteta, večja okoljska sprejemljivost in možnost uporabe virov iz biomase. Sintetizirali smo več organskih katodnih materialov na osnovi pirazinskih in kinonskih enot ter njihovo delovanje preizkusili z galvanostatskimi meritvami v modelnem litijevem akumulatorju, del smo jih preizkusili tudi v modelnem magnezijevem akumulatorju. Sintetizirani 5,14-dihidro-5,7,12,14-tetraazapentacen (DHTAP) na osnovi pirazinskih enot je v prvih ciklih v modelnem litijevem akumulatorju dosegel specifično kapaciteto 180 mAhg-1, ki je blizu teoretični. V strukturo smo z oksidacijo »dodali« kinonske enote, s čimer je 5,7,12,14-tetraaza-6,13-pentacenkinon (TAPK) v modelnem litijevem akumulatorju v prvi praznitvi dosegel specifično kapaciteto 324 mAhg-1 pri višji napetosti kot DHTAP. Pri obeh sintetiziranih spojinah smo med galvanostatskimi meritvami opazili postopno upadanje specifične kapacitete zaradi odtapljanja aktivnega materiala v elektrolit. Problem topnosti katodnega materiala v elektrolitu smo reševali z vključitvijo osnovne strukturne enote DHTAP v povečan zvezdast analog, kjer smo za sintezo uporabili heksaketocikloheksan oktahidrat, derivat mio-inozitola, ki ga je možno pridobiti iz biomase. S tem smo povečali stabilnost delovanja in hkrati povečali tudi specifično kapaciteto, ki je dosegla 230 mAhg-1 in se v 100 ciklih ni bistveno spremenila. Zvezdastemu analogu smo z oksidacijo, analogno kot pri manjšem TAPK, v strukturo »dodali« kinonske enote. Učinek je bil slabši od pričakovanega, saj je s K2Cr2O7 oksidiran produkt v prvi praznitvi dosegel 173 mAhg-1, kar je skoraj polovico manj od TAPK, hkrati pa je bil material kljub večji velikosti molekule topen v elektrolitu, kar je privedlo do postopnega upadanja specifične kapacitete. Z reakcijo med 2,3-diaminofenazinom in 2,5-dihidroksi-1,4-benzokinonom smo poskušali sintetizirati povečan dimerni analog DHTAP. Z MALDI-TOF masno spektrometrijo smo ugotovili, da sinteza ni bila uspešna, produkt pa najverjetneje vsebuje oligomere 2,3-diaminofenazina. Produkt smo preizkusili v modelnem litijevem akumulatorju, kjer je dosegel stabilno kapaciteto, ki je po 100 ciklih znašala 187 mAhg-1. Najpogosteje uporabljeni pristop za zmanjšanje topnosti katodnega materiala v elektrolitu predstavlja oligomerizacija/polimerizacija osnovne strukturne enote; v ta namen smo s kondenzacijsko reakcijo med heksaketocikloheksan oktahidratom in tetraamino-p-benzokinonom poskušali v polimer/oligomer hkrati vključiti kinonsko in pirazinsko strukturo. Sintetizirani material je v modelnem litijevem akumulatorju dosegel slabšo specifično kapaciteto od pričakovane, okoli 120 mAhg-1, a z boljšo stabilnostjo, saj nismo opazili odtapljanja aktivnega materiala v elektrolit.

Ključne besede

organski katodni materiali;kinon;pirazin;baterije;akumulatorji;magnezijeva anoda;magistrska dela;

Podatki

Jezik: Slovenski jezik
Leto izida:
Tipologija: 2.09 - Magistrsko delo
Organizacija: UL FKKT - Fakulteta za kemijo in kemijsko tehnologijo
Založnik: [S. Menart]
UDK: 621.355:547.567:547.86(043.2)
COBISS: 31337475 Povezava se bo odprla v novem oknu
Št. ogledov: 425
Št. prenosov: 94
Ocena: 0 (0 glasov)
Metapodatki: JSON JSON-RDF JSON-LD TURTLE N-TRIPLES XML RDFA MICRODATA DC-XML DC-RDF RDF

Ostali podatki

Sekundarni jezik: Angleški jezik
Sekundarni naslov: Electroactive materials based on pyrazine and quinone units
Sekundarni povzetek: Currently used batteries in electric vehicles have cathodes consisting of inorganic materials based on transition metals. Recently an alternative to inorganic cathodes has emerged in the form of organic cathode materials, which benefit from lower costs, higher theoretical capacities, lower environmental impact and the option to use biomass derivates. We synthesized several organic cathode materials based on quinone and pyrazine units and tested them with galvanostatic measurements in a model lithium battery, some of them were also tested in a model magnesium battery. Synthesized 5,14-dihydro-5,7,12,14-tetraazapentacene (DHTAP) based on pyrazine units delivered a specific capacity of 180 mAhg-1 in the first cycles, which is close to its theoretical capacity. With oxidation of DHTAP quinone units have been »added« into the structure, which increased the potential and specific capacity of 5,7,12,14-tetraaza-6,13-pentacenequinone (TAPQ) reaching 324 mAhg-1 in the first discharge of a model lithium battery. Both synthesized materials showed gradual capacity fading due to the dissolution of the active material in the electrolyte. We tried to solve this problem and improve the battery characteristics by incorporating the basic structural unit of DHTAP into a bigger star shaped molecule using a hexaketocyclohexane octahydrate, a derivate of myo-inositol, a compound obtained from waste biomass. Synthesized material showed improved cycling stability delivering a specific capacity of 230 mAhg-1, which remained constant throughout 100 cycles. We employed the same strategy of incorporating quinone units into the star shaped DHTAP analogue through the oxidation process. The oxidation of the material did not bring expected results, as the oxidized material reached specific capacity of 173 mAhg-1 in its first discharge, which is only a half of the capacity of TAPQ. The oxidized material was also soluble in the electrolyte, which was the reason for the observed fast specific capacity fading. We tried to employ a reaction between 2,3-diaminophenazine and 2,5-dihydroxy-1,4-benzoquinone to synthesize a bigger DHTAP analogue. The analysis with MALDI-TOF mass spectrometry showed, that the synthesis did not deliver the expected product, which is probably comprised of the oligomers of 2,3-diaminophenazine. We tested the obtained product in a model lithium battery in which it delivered a specific capacity of 187 mAhg-1 in the 100th cycle with slow capacity fading. Most commonly used strategy to prevent the dissolution of the active material in the electrolyte is the incorporation of the basic structural unit into an oligomer/polymer. In order to employ this strategy, we used a condensation reaction between hexaketocyclohexane octahydrate and tetraamino-p-benzoquinone. Obtained product delivered a lower than expected specific capacity of 120 mAhg-1 in a model lithium battery, without the dissolution of the active material in the electrolyte.
Sekundarne ključne besede: batteries;quinone;pyrazine;organic cathode materials;
Vrsta dela (COBISS): Magistrsko delo/naloga
Študijski program: 1000375
Konec prepovedi (OpenAIRE): 1970-01-01
Komentar na gradivo: Univ. v Ljubljani, Fak. za kemijo in kemijsko tehnologijo, smer Kemija
Strani: 72 str.
ID: 12033163